Microbiology 5.4: Escherichia coli Flashcards

Questions and Answers

E. coli does ferment lactose.

True

What antigen is present on the capsule of E. coli?

K antigen

When E. coli grows on ___ agar, it produces a green sheen.

EMB agar

When E. coli grows on EMB agar, it produces a ___ sheen.

green Signup and view all the answers

E. coli is catalase negative.

False Signup and view all the answers

What virulence factor of E. coli plays a part in urinary tract infections?

Fimbriae or pili Signup and view all the answers

E. coli is the number one cause of ____.

urinary tract infections Signup and view all the answers

E. coli is the leading cause of gram-negative ____.

sepsis Signup and view all the answers

E. coli's ability to cause sepsis is due to the virulence factor, ___.

lipopolysaccharide (LPS toxin located on the outer cell membrane) Signup and view all the answers

The K antigen virulence factor causes what disease?

neonatal meningitis Signup and view all the answers

EHEC is commonly transmitted from ____.

eating undercooked hamburgers Signup and view all the answers

EHEC will present with what GI complaint?

bloody diarrhea Signup and view all the answers

EHEC _ lactose and _ sorbitol.

ferments lactose but does not ferment sorbitol Signup and view all the answers

EHEC's virulence factor is ___. Where does it bind?

Shiga-like toxin; it binds to the 60S ribosome unit Signup and view all the answers

Shiga-like toxin can cause what disease in children, especially those under 10 years old?

hemolytic uremic syndrome Signup and view all the answers

What is the MOA of hemolytic uremic syndrome?

Shiga-like toxin damages endothelial cells in capillary linings, causing platelet aggregation and schistocytes Signup and view all the answers

What serotype is associated with outbreaks?

EHEC serotype O157 Signup and view all the answers

ETEC is associated with what disease?

traveler's diarrhea Signup and view all the answers

ETEC is transmitted via what?

water Signup and view all the answers

What are the ETEC toxins?

heat-labile increases cAMP; heat-stabile increases cGMP Signup and view all the answers

Which of the ETEC toxins is similar to cholera?

the heat-labile one that increases cAMP Signup and view all the answers

The diarrhea caused by ETEC is bloody.

False Signup and view all the answers

Study Notes

Escherichia coli Overview

E. coli ferments lactose, categorizing it as a lactose fermenter.
K antigen present on E. coli’s capsule indicates its encapsulated nature.

Culturing E. coli

E. coli produces a green sheen when cultured on EMB agar.

Biochemical Characteristics

E. coli is catalase positive, which contributes to its survival in the presence of hydrogen peroxide.

Pathogenicity

Fimbriae (pili) are a key virulence factor responsible for urinary tract infections.
E. coli is the most common cause of urinary tract infections and is a leading cause of gram-negative sepsis.
Lipopolysaccharide (LPS) acts as a virulence factor, enabling E. coli to cause sepsis.

Specific Diseases Caused by E. coli

The K antigen is implicated in neonatal meningitis.
EHEC (Enterohemorrhagic E. coli) is typically transmitted through undercooked hamburgers and causes bloody diarrhea.
EHEC ferments lactose but does not ferment sorbitol, differentiating it from other types.
Shiga-like toxin is a virulence factor of EHEC, targeting the 60S ribosomal subunit and can lead to hemolytic uremic syndrome, affecting children under 10.

Mechanism of Hemolytic Uremic Syndrome

Shiga-like toxin damages endothelial cells, leading to platelet aggregation, which fragments passing red blood cells, resulting in schistocytes.

EHEC Serotype

Serotype O157:H7 is frequently associated with outbreaks of EHEC.

Traveler's Diarrhea and ETEC

ETEC (Enterotoxigenic E. coli) causes traveler's diarrhea, primarily transmitted through contaminated water.
ETEC toxins include heat-labile toxin, which increases cAMP, and heat-stabile toxin, which increases cGMP.
The heat-labile toxin shares similarities with cholera toxin.

Clinical Presentation of ETEC

Diarrhea caused by ETEC is typically nonbloody and characterized by watery stools.

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Description

This quiz focuses on key characteristics of Escherichia coli, including its ability to ferment lactose and the specifics of its growth on EMB agar. Test your knowledge of its antigens and other defining traits with these flashcards. Perfect for students studying microbiology!